The repair shop reset the light yesterday and did another meter check again today. Although the "check engine" indicator light is off, it seems the codes are still active and would continue to cause my Quest to fail inspection. I wonder if there is any other way to resolve the "Knock Sensor" readout problem, short of the $500 sensor replacement repair? Some comments seem to suggest that high octane gas and/or new plugs might correct the problem. I've also seen a suggestion that disconnecting the battery for 90 minutes might help with this issue too? Any ideas?

knock sensor codes do not fail vehicles for inspection in my state. all that is required is all the readiness codes are set wich basically means the check engine light has to be off. knock sensors do not turn on the light and do not effect readiness codes. but the rules may be different in your state. i live in nc.

The knock sensor does not turn on the check engine light. It should not be a problem for inspection. At least not in new york state where I live. As long as the light is not on they usually pass. If you wanted to just get by to pass inspection you could buy a knock sensor and the short sub harness that goes to it. The knock sensor sub harness plugs in by the drivers side of the front cylinder head. It is easily accessible. If you plugged in a good sensor you would be able to clear the code. Might be woth going to the dealer for the sub harness and then an aftermarket part supplier for the knock sensor. You would have a better chance of returning the part if you wanted to after the inspection.

It's troubling to hear so many stories of folks going for the $500-$600 repair bills to replace the knock sensor, only to have the trouble code persist. I do remain a bit puzzled by the fail/pass question as determined by the faulty knock sensor code. My confusion stems from reading the "NYS DMV Inspection Receipt" for my '99 Quest. The receipt indicates that my vehicle passed the safety inspection but "has failed the emissions inspection." The OBDII diagnostic trouble codes were:

Knock sensor (P0325) and
Vehicle Speed Sensor "A" (P0500)

The impression given to a laymen like myself seems to be that a repair of the conditions/codes is required to pass the inspection. Tomorrow I will get my transmission speed sensor installed and then I'll go with the advice of you kind professionals. Friday I will try the inspection routine once again. I'll be sure to post my results so that it might help another Knock Sensor victim.
I hope I'm not "knocking" this Knock Sensor thing "senseless".

I managed to get my '99 Quest speed sensor problem fixed, but I still have the knock sensor code that won't go away. I've ordered the sub harness from a local Nissan dealer but I can't get any local repair people to touch this with a 10 foot socket extension. Although they go on about liability issues and all that I can't help thinking that they just want that $400-$600 labor charge ti take the upper engine apart and do the "by the book" KS replacement. I expect the sub harness to arrive today or tomorrow and it looks like I'm doing this alone. I wonder if you could please help me out with any '99 Quest fotos or precise description indicating the exact sub harness connector to which I must connect the new knock sensor sub harness plug? In an effort to trace the wires back to the proper connector, I tried looking into the "V" valley where the KS is mounted on the engine but I can't see a darn thing. It looks like it's well buried and behind all sorts of other stuff. As always, your help is greatly appreciated.

yeah the knock sensor is located in the center of the intake on the block. i would just unplug the harness and use the new subharness to relocate the knock sensor to a different location on the engine. it is held in place with a 12mm bolt. just find a bolt and an extra hole in the head or intake and put it there. there should not be any problems with doing that.

I appreciate your response. I'm just not real sure what the end plug of the sub harness looks like since i can't trace it back from the KS. Once I can locate that plug and find the right spot, to mount the new KS I'm sure the rest should be easy. Perhaps when I get the harness I will recognize which plug is the match up front. Thanks for your help.. I'll let you all know how a real laymen does with this project.

Well folks.. HELLLLLLLP!
Jut thought I'd drop in to report my lack of progress with this knock sensor replacement and to BEG for HELP!!

I got a bad knock sensor code (P0325) on my 99 Quest van and the DMV folks tell me that this will cause an inspection emissions failure in NY and NJ.
As advised, I purchased a new knock sensor and sub harness (running from the ks to an engine compartment connector). I was supposed to find the engine compartment end of the harness, plug in the new knock sensor and then mount it securely elsewhere on the engine. My problem is that i cannot find the engine compartment end of the ks sub harness to plug into. This ks replacement seems like a simple, straightforward and inexpensive solution, but only if one can find the right connector. Could anyone please direct me by description or a reference foto that might help? Staring into the engine compartment for long periods of time hasn't helped..

Hey Bobby, Just checking in to see if you ever got this resolved? Thinking I might go the replace it myself route and was seeking the final advice that you apparantly never recived. THANKS! Jon

Quote:

Originally Posted by bobbyknapp

Well folks.. HELLLLLLLP!
Jut thought I'd drop in to report my lack of progress with this knock sensor replacement and to BEG for HELP!!

I got a bad knock sensor code (P0325) on my 99 Quest van and the DMV folks tell me that this will cause an inspection emissions failure in NY and NJ.
As advised, I purchased a new knock sensor and sub harness (running from the ks to an engine compartment connector). I was supposed to find the engine compartment end of the harness, plug in the new knock sensor and then mount it securely elsewhere on the engine. My problem is that i cannot find the engine compartment end of the ks sub harness to plug into. This ks replacement seems like a simple, straightforward and inexpensive solution, but only if one can find the right connector. Could anyone please direct me by description or a reference foto that might help? Staring into the engine compartment for long periods of time hasn't helped..

Well Jon,
i never did get any strong instruction on how to find the accessible end of the knock sensor cable in the engine compartment. As advised, i bought a new sensor and harness to do the repair but i still don't know where it hooks up to. i was hoping that someone could give me a foto or a specific description but so far no one has offered. i tried accessing the repair manual here but wasn't able to get in .. Perhaps i will try that again. i have only weeks to get my car inspected before my registration runs out so i am getting a bit desperate. My next move might be to the nissan dealer to try and tip a technician there if one was nice enough to point out exactly where it is that i need to plug into. And hey.. Thanks for asking.. i thought i just was wasting away there in knock sensor limbo...
Cheers, bob

Well Jon,
i never did get any strong instruction on how to find the accessible end of the knock sensor cable in the engine compartment. As advised, i bought a new sensor and harness to do the repair but i still don't know where it hooks up to. i was hoping that someone could give me a foto or a specific description but so far no one has offered. i tried accessing the repair manual here but wasn't able to get in .. Perhaps i will try that again. i have only weeks to get my car inspected before my registration runs out so i am getting a bit desperate. My next move might be to the nissan dealer to try and tip a technician there if one was nice enough to point out exactly where it is that i need to plug into. And hey.. Thanks for asking.. i thought i just was wasting away there in knock sensor limbo...
Cheers, bob

I pulled this from your Service Manual SECTION EC - Engine Control System.

Thanks VP, but the schematics still don't help me locate the engine compartment end of the knock sensor harness. As per the simpler and much less costly solution recommended by your colleagues (plugging a new harness and knock sensor into the engine compartment plug instead of ripping everything off the engine to replace the original sensor), i still need to find that engine compartment plug. i see that there are references made to the terminal ends of the connector harness (F212;F213) but i still don't know how i can find that terminal under the hood. i guess i'll hang in there and see how i can get past that problem. There's always your buddies at the dealership i guess... Thanks very much though....
bob

The connector should be on the drivers side of the engine. Look at the front valve cover on the end towards the transmission. You should be able to find the connector there. Take the new harness and match up the plug.

Dear MPE,
i appreciate the response. i've looked under the hood there before and just can't make out where the plug is. i will continue to look though.... Maybe with some luck a knowing finger will point the way to the spot.. gotta keep the faith...! Thanks again!